Current Behavior

currently, apisix gets the "X-Forwarded-Proto" header when calling the set_upstream_headers function,

https://github.com/apache/apisix/blob/master/apisix/init.lua#L228-L239

but it reads all the headers first, which may cause the CPU to rise abnormally if the number of headers is very large and the size is large

https://github.com/apache/apisix/blob/master/apisix/core/request.lua#L45-L66

Expected Behavior

No response

Error Logs

No response

Steps to Reproduce

none

Environment

• APISIX version (run apisix version):
• Operating system (run uname -a):
• OpenResty / Nginx version (run openresty -V or nginx -V):
• etcd version, if relevant (run curl http://127.0.0.1:9090/v1/server_info):
• APISIX Dashboard version, if relevant:
• Plugin runner version, for issues related to plugin runners:
• LuaRocks version, for installation issues (run luarocks --version):